Water circulator



Oct. 7, 1941. M. o. THRUSH 2,257,867-

WATER CIRCULATOR Filed Sept. 27, 1940 QUODW 28 Patented Oct. 7, 1941 UNITED STATES PATENT OFFICE WATER CIRCULATOR Marquis 0. Thrush, Peru, Ind., assignor to The Thrush Company, Peru, Ind.

Application September 27, 1940, Serial No. 358,735

9 Claims.

This invention relates to a water circulator for installation in a hot water heating system and the like for establishing a forced circulation of water through such a system.

The use of heating systems utilizing forced circulation have increased to a point where they are now used in homes and buildings of all types regardless of cost. This has created a demand in the market for circulators of relatively low cost, small and compact yet with.

a high degree of efficiency; and it is an object of the present invention to provide a circulator which will meet these requirements.

The present invention is primarily directed to the construction of the impeller for water circulators. Heretofore, as far as known, water circulators of a commercially practical-type have utilized impellers of cast metal. This necessitated care in the casting operation, machining of the completed casting and testing for balance. Furthermore, cast impellers are relatively heavy and have a relatively high moment of inertia. Due to the fact that circulators in heating systems are constantly being started and stopped, and when in operation rotate at a high rate of speed, it is extremely desirable that the impellers be as light in weight as possible to reduce inertia, power costs, noise and vibration and avoid wear on the bearings.

The impeller of the present invention is designed so that it may be made from sheet metal stampings which when mated and. assembled result in a construction which is unusually light in weight, has a high degree of efficiency, is stable and quiet at all speeds, and may be manufactured and assembled at an unusually low cost. Further, the construction of the impeller is such as to interpose a minimum of resistance to free circulation of water through the impeller housing, a feature of importance in modern hot water heating systems.

In the drawing:

Fig. 1 is a perspective of a water circulator in accordance with the present invention;

Fig. 2, an enlarged fragmentary detail section of the lower portion of Fig. 1; c

Fig. 3, a bottom plan of the impeller;

Fig. 4, a transverse section taken substantially on line 44, Fig. 3;

Fig. 5, a perspective of the impeller shaft bearing and lubricating member; and

Fig. 6, an enlarged section taken through the impeller shaft thrust bearing assembly.

Referring to the drawing a circulator casing I is provided with an inlet conduit I I and an outlet conduit I2. The inlet conduit is spanned by the wall I3, which constitutes a dividing'memher for the water flowing into the-chamber through the said inlet.

The impeller is generally indicatedat I4, and is made from a pair of sheet metal'stampings shaped to provide upper and lower discs I4 and l4 which when mated form the complete impeller. The metal may be brass, a suitable non-corrosive alloy or th like. The upper" disc has blades I5 struck from its peripheral portion and the lower disc has similar blades I B. The manner in which the blades are formed is best shown in Fig. 3. At spaced intervalsaround the peripheral area of the disc the metal is stamped out along the line I! and the metal struck upwardly, leaving a slot which is open' at the periphery of the disc a indicated at H. The up-struck metal of the slot provides a blade which is rounded at its inner'corner and tapers as it approaches the peripheryv of the disc. The blade is preferably located in a radial plane extending at a tangent to the axis of the impeller to obtain maximum efliciency.

The blades I6 of the lower disc I4 are formed in a manner similar to the blades I5 of the upper disc. However, in-this'instance the blades are arranged so that they are in staggered or alternate relation with the blades I5. In other words, the blades of the lower disc alternate with respect to the blades of the upper disc. This not only increases the efliciency of the impeller, but also causes the metal of one disc to cover the slots of the other disc.

To ensure accurate positioning of one disc with respect to the other, they are properly paired and depressions I8 are then punched in the mated discs, thereby forming a projection I8 in one disc which mates with a depression I8 in the other disc. This provides a means whereby the disc may be easily and quickly brought together in proper mating relation during the assembling operation, and when as-' sembled, ensure against relative displacement of the discs.

The-discs as initially formed are given a dished contour as indicated at I9 in Fig. 4. This contour is preferably imparted to the discs at the time they are formed. When the discs are assembled on the impeller shaft, they are thus brought together under tension, insuring against displacement of the discs with respect to the shaft and also resulting in a unit which is free from noise or rattling while in operation. Fig. 4 shows the discs mated ready for threading on the lower end of the impeller shaft, while in Fig. 2 the discs are mounted. Note in the latter figure how the discs are drawn together under tension with adjacent surfaces in contact throughout their entire area.

The bottom disc I4 has a central collar 20 stamped therefrom which is interiorly threaded, while the upper disc is provided with a like collar 2| which is smooth or unthreaded. Thus when the discs are assembled on the impeller shaft, indicated at 22, note particularly Fig. 2, the lower threaded end of the shaft engages the lower disc and draws the lower disc against the upper disc and the latter in tight, abutting relation with a shoulder 23 formed on the shaft. Since the impeller rotates in a direct counter to the threads of the collar 20, there is no tendency for the impeller to become displaced from the shaft.

It will be noted that the impeller blades start well out from the center of the disc, leaving a large central area free. This facilitates gravity circulation of water through the circulator, and consequently facilitates free circulation of water through a hot water system in which the circulator may be installed.

It will be seen that with an impeller of the type above described, unusual lightness in weight may be attained, while at the same time all machining is eliminated. Due to the fact that sheet metal is more dense and of a finer grain, and further, due to the accuracy with which the stamping operation may be carried out, all balancing and testing is eliminated. Thus a single operator may produce the present impeller with a stamping machine, whereas cast impellers generally require two operators for balancing and testing and a turret lathe for machining. Also, the impeller is materially reduced in weight with respect to cast metal, being only about 25% to 30% as heavy, thereby reducing the 'moment of inertia and the energy required to start the circulator, and there is also less strain on the bearings. Actual experience has demonstrated that considerably greater efiiciency may be obtained with the same volume of fluid flow.

The impeller chamber is indicated at 24 and is defined in part by upper and lower shroud plates 24 and 24 which are detachably anchored in the openings formed in the wall 13.

The casing or housing H) has mounted thereon a bonnet or bracket 25, and the impeller shaft 22 projects upwardly or outwardly through said bracket and at its upper end is connected to a flexible shaft coupling generally indicated at 26. A driving motor 21 is mounted on the bracket 25 through the medium of resilient connections 28 which latter connections serve as noise and vibration dampeners and ensure constant alignment of the motor shaft with the impeller shaft.

Between the casing I and the bracket or pocket 25 is a lubricating and bearing member generally indicated at 30, which forms the subject matter of a separate application. Briefly stated, however, this bearing and lubricating member comprises a base portion 3| in which is a sump or well 32 adapted to receive absorbent material 32 for retaining a lubricant for the shaft 22. Projecting upwardly from the well is a bearing 33 having spiral oil grooves 34 formed on the interior thereof, the oil from the sump or well 32 passing in through slot or opening 35 and being carried upwardly in the grooves 34 due to rotation of shaft 22 and capillary ac tion, and then overflowing the exterior of the bearing 22 and passing by gravity back to the well or sump.

Below the bearing member 30 is a thrust bearing assembly comprising retainer ring 31 having an annular cavity 38 therein in which is disposed a resilient cushioning ring 39 and a carbon bearing ring 40. A sleeve 4| is secured on the lower end of shaft 22, said sleeve constituting an extension of retainer ring 31.

In assembling the parts of the circulator, the shaft 22 with the thrust bearing assembly thereon may be inserted through the bearing and lubricating member 3! and hood or bracket 25. The impeller discs l4 and i4 in matched or mated relation as illustrated in Fig. 4 may then be assembled onto the lower end of the shaft, the collar 2| abutting the sleeve or'shoulder [3 while the interior threaded collar 20 is drawn up into tight engagement with the plate H. The parts may then be inserted in the impeller chamber, the shroud plate 24 secured in place and the bonnet or hood 25 bolted onto the easing Hi.

It wil1 be understood that certain changes in construction and design may be made without departing from the scope or spirit of the invention as defined by the appended claims.

I claim:

1. In a circulator for hot water heating systems and the like, a casing having an impeller chamber therein, an impeller shaft projecting into said chamber, bearing means for said shaft, and an impeller secured on the end of said shaft for rotation in said impeller chamber, said impeller comprising a pair of sheet metal discshaped stampings each of which has struck from the peripheral portion thereof a series of blades leaving an open slot for each blade, said blades extending in a direction substantially tangential with respect to said shaft, the central portion of the upper or inner disc being formed with an opening having an unthreaded collar therearound and the central portion of the lower or outer disc being formed with an opening having an interiorly threaded collar therearound, the lower or outer end of said shaft being threaded and provided with a shoulder whereby when the discs are assembled thereon the outer disc draws the inner or upper disc against said shoulder and clamps both discs together, said discs being mated in a manner such that the blades of one disc are in alternate or staggered relation with the blades of the other disc and the metal of one disc covers the slots of the other disc, the discs having the central portions thereof initially stamped with oppositely disposed concavities so that when the discs are drawn together all adjacent surface areas are held in contact under tension, and registering index projections and depressions formed in the mating surfaces of said discs to ensure proper positioning of the latter and lock the discs against displacement.

2. In a circulator for hot water heating systems and the like, a casing having an impeller chamber therein, an impeller shaft projecting into said chamber, bearing means for said shaft, and an impeller secured on the end of said shaft for rotation in said impeller chamber, said impeller comprising a pair of sheet metal discshaped stampings each of which has struck from the peripheral portion thereof a series of blades leaving an open slot for each blade, said discs being mated in a manner such that the blades of the other disc and the metal of one disc covers the slots of the other disc, said discs having the central portions thereof initially stamped with oppositely disposed concavities so that when the lower or outer disc is threaded on the end of the shaft the discs are drawn tightly together under tension with all adjacent surface areas in contact, said discs being formed with indexing projections and depressions which register when the discs are drawn together and lock the discs against displacement.

3. In a circulator for hot water heating systems and the like, a casing having an impeller chamber therein, an impeller shaft projecting into said casing, bearing means for said shaft, an impeller secured on the end of said shaft for rotation in said impeller .chamber, said impeller comprising a pair of sheet metal disc stampings each of which has struck from the peripheral portion thereof a series of blades leaving an open slot for each blade, said discs being mated in a manner such that the blades of one disc are in alternate or staggered relation with the blades of the other disc and the metal of one disc covers the slots of the other disc, and means for indexing said discs to facilitate assembly, said indexing means also operating to hold said discs against displacement during operation of the impeller.

4. In a circulator for hot water heating systems, a casing having an impeller chamber therein, an impeller in said chamber, an impeller shaft supporting said impeller, said impeller comprising a pair of dish-shaped sheet metal stampings with a series of blades struck from the peripheral portions thereof, open slots being left in the portion of the disc from which the blades were struck, said discs being so mated on said shaft that the blades of one disc are in alternate or staggered relation to the blades of the other disc and the slots of one disc are covered by the other disc, means for fastening said discs in assembled relation, said discs being oppositely concaved, the concavity extending substantially from the central to the peripheral portions, so that when drawn together they are under tension with the greatest tension at the remotest distance from their centers.

5. In combination a pump for producing forced circulation of liquid comprising a casing having an impeller chamber therein, an impeller in said chamber and a shaft for supporting said impeller, said impeller comprising a pair of blade carrying dished sheet metal discs the concavity extending substantially from the central to the peripheral portions, and assembled with their dished portions facing each other to provide a complete impeller unit, and means for maintaining said discs in assembled relation under tension with the greatest tension at the remotest distance from their centers.

6. An impeller for the propulsion of liquid comprising a pair of complementary pressed relatively thin blade-carrying metal discs assembled with the same axis to provide a complete impeller unit, at least one of said discs being dished relative to: the other progressively from its peripheral portion to its central portion so that in assembly the periphery of said disc will first come in contact with the cooperating disc, means for maintaining said discs in assembled relation under tension, the construction and arrangement being such that the greatest tension on the discs is at the remotest distance from their centers.

7. An impeller for producing forced circulation of liquid comprising complementary blade-carrying body members of stamped sheet metal at least one of said body members having its periph:

' tion with their peripheries under tension.

8. An impeller for producing forced circulation of liquid comprising complementary bladecarrying body members stamped from sheet metal, at least one of said body members having a concave surface, the concavity extending substantially from the central to the peripheral portions, said body members being in engagement with the concave surface facing the other body member, and means for maintaining said body members in assembled relation under tension.

9. For use in a house heating system including liquid conduits, means for producing forced circulation of liquid in said conduits comprising a casing having an impeller chamber therein, an impeller in said chamber consisting of two sheet metal stampings with a series of blades struck from the peripheral portions thereof, open slots being left in the portions of the stampings from which the blades were struck, said stampings being so united that the blades of one stamping are in alternate or staggered relation to the blades of the other stamping and the slots of one stamping are covered by the other. stamping, means for fastening said stampings in assembled relation with their bodies substantially parallel and in contact, the inner ends of said blades terminating outwardly of the center of the 1m,- peller and permitting free circulation of liquid across the impeller through said casing when the impeller is idle.

MARQUIS O. THRUSH. 

